Propagate HTTP header (JWT Token) over services using spring rest template

dragonalvaro :

I have a microservice architecture, both of them securized by spring security an JWT tokens.

So, when I call my first microservice, I want to take the JWT token and send a request to another service using those credentials.

How can I retrieve the token and sent again to the other service?

dragonalvaro :

I've accomplished the task, creating a custom Filter

public class RequestFilter implements Filter{



    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {

        HttpServletRequest httpServletRequest = (HttpServletRequest) request;
        String token = httpServletRequest.getHeader(RequestContext.REQUEST_HEADER_NAME);

        if (token == null || "".equals(token)) {
            throw new IllegalArgumentException("Can't retrieve JWT Token");
        }

        RequestContext.getContext().setToken(token);
        chain.doFilter(request, response);

    }

    @Override
    public void destroy() { }

    @Override
    public void init(FilterConfig arg0) throws ServletException {}


}

Then, setting in my config

    @Bean
public FilterRegistrationBean getPeticionFilter() {

    FilterRegistrationBean registration = new FilterRegistrationBean();
    registration.setFilter(new RequestFilter());
    registration.addUrlPatterns("/*");
    registration.setName("requestFilter");

    return registration;
}

With that in mind, I've create another class with a ThreadLocal variable to pass the JWT token from the Controller to the Rest Templace interceptor

public class RequestContext {

public static final String REQUEST_HEADER_NAME = "Authorization";

private static final ThreadLocal<RequestContext> CONTEXT = new ThreadLocal<>();

private String token;

public static RequestContext getContext() {
    RequestContext result = CONTEXT.get();

    if (result == null) {
        result = new RequestContext();
        CONTEXT.set(result);
    }

    return result;
}

public String getToken() {
    return token;
}

public void setToken(String token) {
    this.token = token;
}

}

public class RestTemplateInterceptor implements ClientHttpRequestInterceptor{

@Override
public ClientHttpResponse intercept(HttpRequest request, byte[] body, ClientHttpRequestExecution execution) throws IOException {

    String token = RequestContext.getContext().getToken();

    request.getHeaders().add(RequestContext.REQUEST_HEADER_NAME, token);

    return execution.execute(request, body);

}

}

Add interceptor to the config

  @PostConstruct
public void addInterceptors() {
    List<ClientHttpRequestInterceptor> interceptors = restTemplate.getInterceptors();
    interceptors.add(new RestTemplateInterceptor());
    restTemplate.setInterceptors(interceptors);
}